Flexible abrasive wheel



Oct. 8, 1957V G.' G. THOMSON ETAL 2,808,689

FLEXIBLE ABEAsIvE WHEEL Filed Aug. s. 195e f la f2 INVENTORJ /FZ G /L'Zg 5 gagna/v 6. #MM50/w BY .00A/1ra 2.4475554 FLEXIBLE ABRASIVE WHEEL Gordon G. Thomson, Rocky River, and Donato P. Latessa, Willowick, Ohio Application August 8, 1956, Serial No.76072,691

4 Claims. (Cl. 51-193.5)

This invention relates to flexible abrasive wheels and particularly to the type of abrasive wheels in which flaps of fabric, each of which is coated on at least one face with abrasive material, are arranged in closely packed face to face relation in an annular row which extends about a hub and which, at its inner lateral margins, is clamped between face-plates of an arbor which is coaxial with the annular row and hub and is so arranged that, upon driving of the arbor and pressing `a workpiece radially against the wheel the abrasive faces of the individual flaps of the wheel iiex so as to present their abrasive faces to the workpiece and successively wipe against its surface.

Heretofore, wheels of this character have been formed by arranging the abrasive flaps in face to face relation in a straight row and cementing a flexible fabric strip to their inner ends and thereafter laying the fabric binding strip around a hub so as to dispose the flaps radially of the hub. ln other wheels of this character, the flaps are mechanically secured in place by various holding devices. In wheels of this type, the axes of the annular row, of the hub, and of the arbor should coincide. Further, within the annular row, as many flaps as possible, consistent with sufficient clearance between the operating portions of the flaps so that the aps can ilex ilatwise and present their abrasive faces rather than their ends to the workpiece, should be provided. This optimum close association of the iiaps should be persent regardless of the diameter of the wheel. Furthermore, the inner ends of the iiaps should be securely anchored. The wheel should be so arranged that it can be fabricated readily from readily available materials.

Various objects and advantages of the present invention will become apparent from the following description wherein reference is made to the drawings, in which:

Fig. l is a side elevation of an abrasive wheel embodying the principles of the present invention and viewed axially of the wheel, parts thereof being shown in section and other parts thereof being broken away for cleanness in illustration;

Fig. 2 is a cross sectional view taken on the line 2-2 of Fig. l, the abrasive flaps and part of the arbor being shown in elevation for clearness in illustration;

Figs. 3 and 4 are a side elevation and front elevation of a retaining ring which may be used in the present invention;

Fig. 5 is a front elevation of one of the abrasive flaps used in the present wheel:

Fig. 6 is a cross sectional view taken on the line 6-6 in Fig. 5; and

Fig. 7 is a view similar to Fig. 2 showing a modification of the invention;

Fig. 8 is a front elevation of a modified form of one of the abrasive flaps; and

Fig. 9 is -a cross sectional view taken on line 9-9 of Fig. 8.

Referring to the drawings, the wheel comprises a plurality of fabric flaps 1 arranged in face to face relation in an annular row, as best illustrated in Fig. l.

Inite States Patent O cement.

2,8%,689 Patented Oct. 8, 1957 ice The individual flaps are composed of fabric, as indicated at 2, each having on at least one face an abrasive Each of the flaps 1 is provided at its opposite edges `with lateral notches 4 which open laterally of the ap.

The notches 4 are so arranged that when the flaps I are 'p assembled in an annular row, the notches 4 provide annular channels, indicated at 5 in Figs. l and 2, which are Ycoaxial with the central opening of the annular row. The

channels 5 are spaced outwardly from the inner ends 6 of the flaps 1 part-way toward the outermost ends 7 thereof. When the aps 1 are assembled in the annular row, rigid annular locking rings 8 are disposed within the .channels 5, respectively. Further, each-flap 1 is provided with an aperture 9 which is disposed near its inner end 6 and inwardly, endwise of the flap, from its notch. The apertures 9 are arranged olf-center, laterally of the iiaps, so that when theaps are assembled in the annular i row with the abrasive faces all facing in the same direction, the apertures 9 will be aligned and provide an annular passage. An annular retaining ring, such as indicated at 10 in Fig. 3, extends through the aligned apertures 9. VAs there shown, the retaining ring is a split ring, its split being indicated at 11, of which the end portions adjacent the split can be spread apart laterally or axially of the ring to -perrnit threading the flaps 1 onto the 4ring by insertion of the ring through the apertures 9,-

successively.

In assembly, a number of flaps are disposed on the ring 10 and after the inner end portions of the iiaps are pressed into rm face to face juxtaposition with each other, the ring ends are permitted or caused to snap back linto alignment to provide a true annulus with the severed portions at the split interlocked.

It is to be noted that, since the apertures 9 are offcenter laterally, if any flap is turned so that its abrasive face is opposite from that of the others, in a directioncircurnferentially of the row, the aperture 9 of the flap thus oppositely turned would be disposed in off-set relation to the apertures 9 of the other liaps so that the ring 10'cannot be inserted. This apprises the operator that a flap is turned so as to face in the wrong direction.

As many flaps las possible are assembled on the ring 10, after which the locking rings 8 are installed. As mentioned, the channels 5 are coaxial with the central opening of the annular row defined by the inner ends 6 of the aps. A rigid hub 12, having an arbor passage there- The hub is of the proper diameter to fit snugly against the inner ends 6 of the aps defining the central opening. With the parts in this assembled condition, a penetrating cement is applied onto the lateral faces of the wheel at an annular area bounded by a'circurnference near or slightly outwardly from the radially outer most extremities ofthe rings 8 and the outer circumference of the hub l2. This cement is such that it flows between the faces of the individual flaps, between the lateral edges of the iiaps and the locking rings 8, between the walls of the apertures 9 and the ring 10, and between the inner ends of the flaps and the hub 12, and, upon setting, bonds all of them firmly together into a unitary structure.

Thus the flaps are arranged with the rings 8, the ring 10, the inner ends 6, and the hub 12 in coaxial relation for mounting on an arbor A.

The notches 5 preferably are arranged outwardly from the axis of the wheel adistance such that they treminate at their radially outermost limits at the radially outermost limits of the usual face-plates 13 of the arbor with which the wheel is to be associated so that the arbor plates 13 firmly engage the rings 8 and constrain them and the flaps from separation laterally ofthe wheel.

It is desirable that the plates 13 be relatively thin at their outermost peripheral margins so as to reduce as Ymuch as possible the chance that the workpiece will be engaged and scued thereby as the workpiece Vis rocked laterally While held against the face of the flaps, particularly as the iiaps wear down close to the lateral peripheries of the plates 13. Accordingly, the plates 13 are bevelled from their outermost peripheral limits 14 inwardlytoward their axes, as illustrated in Fig. v2.

As Vmentioned, it is desirable for many :purposes to place as many flaps in a wheel of given limited diameter as 'possible while at the same time permitting the -aps to flex iatwise circumferentially of the row so that the abrasive faces can wipe against the workpiece. Therefore, in accordance with the present invention, the flaps 1 are made thinner at their inner end portions. As illustrated in Figs. and 6, this preferably is accomplished by skiving oi the abrasive face of each ap for -a limited distance from its linner end 6 outwardly; for example, from a limit such as indicated -at x to a limit such as indicated at y in Fig. 6. In the form of flap illustrated in Fig. 6, the skiving of the abrasive-face may be progressive for ashort distance only so that the flap is gradually decrescent from the limit x to the limit z, and of uniform thickness from the limit z tothe limit y. The thickness of each flap thus is less at its inner limits than at its normal outer abrasiveV operating portions.r Preferably the skiving is such that the normal thickness of the fabric is retained, the fabric not being abraded in any manner at the skived inner end of the flap as full strength of the fabric is desired. Likewise, if the juxtaposed inner end portions of the llaps from the rings 8 to the hub 12 are of no greater thickness than the fabric, an ample number of flaps can be provided in the wheel.

The reduced thickness may be provided in the manufacture of the flaps themselves during their original coating with abrasive but generally such llaps are cut from Ya Wide single piece of material which is` coated to a uniform thickness with abrasive and so the abrasive must be ground off. The skiving off of the abrasive leaves the surface and condition of the fabric at the skived portion particularly susceptive to the bonding cement, in fact, considerably more so than would be the case were the original abrasive permitted to remain on the juxtaposed inner end portions. The skiving, therefore, not only contributes to increasing the number of aps in a Wheel of given hub diameter but also to better bonding of the inner end portions of the flaps 1 to each-other and to contiguous parts.

Referring next to Fig. 7, the wheel is essentially the same as described except that the flaps at their inner end portions, extending from the outer limit indicated by the line a to their inner ends, are reduced in width laterally ofthe' wheel and provide, in effect, a countersink in which the face-plates 15 of an arbor may be disposed so that' the outer lateral limits of the face-plates do not extend outwardly beyond the lateral limits of the flaps themselves. This permits use of the wheel after it has worn down substantially to the outer Aradial limits of the plates 15 Without danger of the kworkpiece being scuifed and marred by engagement with the face-plates themselves.

A retaining ring 16, similar to the'ring 10, may be included.

As illustrated in Figs. 8 and 9, the skiving of each ap may be such that the flap thickness is progressively reduced yfrom the limit indicated by the line r to the inner limit indicated by the line s, thuseliminating any sudden changes in thickness along the length of the inner end portions. In all events, the skiving preferably extends from a location at or just beyond the outer radial limits of the lateral notches of the aps to the inner ends of the flaps.

In accordance with the present invention, a larger number of aps than otherwise would be possible can be assembled in a wheel or given hub diameter, so that more abrasive wipings can be given to a workpiece per rotation of the wheel without any appreciable sacrifice in strength of the wheel. At the same time the outer end portions of the llaps of the wheel are separated sufliciently from each other to permit ready flexibility of the faces so that the faces wipe over the workpiece. Due to the closer assemblage of the flaps circumferentially, the resistance to bending of the flaps away from the workpiece and resultant application of only light pressure to the workpiece is eliminated and instead, each ap is backed up and held more firmly against the workpiece by the closely packed flaps behind it.

Having thus described our invention, we claim:

l. An abrasive wheel comprising a plurality of flaps of fabric, each having on at least one face a coat of abrasive material, each ilap having an outer working portion and an inner end portion which is of less thick- 4ferentially of the wheel and present their faces to the workpiece, the less thickness of the inner end portions -of the flaps being due to a progressive decrease in thicknessof the abrasive coat substantially from the radially outermost limit of the inner end portion at least near to the inner end of the flap, each ap having notches at its opposite lateral limits, the notches being arranged so that, in the assembled wheel, they provide coaxial annular channels extending circumferentially of the assemblage of flaps, annular anchoring means accommodated 'inthe channels, respectively, said inner end portions of reduced thickness terminating radially outwardly from the center of the wheel at a location near the channels, and each ap having an aperture in, and spaced inwardly from the lateral and end margins of, its inner end portion, an Vanular retainer common to all of the flaps and extending through the aperture of each ap, and a central hub tting into the central opening of the annular I 2. An abrasive wheel according to claim l characterlzed in that the apertures of the flaps are offset, each Vthe same predetermined distance, laterally from the middle of the flaps, whereby the abrasive faces of the aps must all face in the same direction in order to permit assemblage of the flaps in the row on the annular retainer.

3. The method of making flexible abrasive wheels from ilaps of fabric coated on at least Vone face with vabrasive grits which are bonded thereto and in which lthe flaps in an annular row with the inner end portions juxtaposed against each other, providing notches in opposite lateral-edges of the flaps so positioned that they provide annular channels at opposite' lateral faces of the assembled row, providing apertures in said inner end portions,` respectively, in alignment in the row, installing annular anchor members in said channels, respectively,

.installing a retaining ring in said apertures, and inserting a hub in the central opening of said annular row.

4. The method according to .claim 3 characterized in the additional step of impregnating the said inner end portions of theaps with apenetrating cement and caus- 5 6 ing the cement to bond the inner end portions of the References Cited in the le of this patent aps together in face to face relation, to bond the lateral UNITED STATES PATENTS edges of the flaps to the annular anchor members and to the retaining ring and to bond the inner end edges of 2,164,800 Davls July 4 1939 the flaps to the hub. 5 2,651,894 Leggett Sept. 15, 1953 2,749,224 Block June 5, 1956 

